Unknown

ABSTRACT

In a device for measuring the axle load of a motor vehicle, at least one extension-sensitive resistor is arranged on at least one component of a motor vehicle which is subject to a change in shape as a function of the load, with at least one insulating layer being arranged in between.

[0001] The invention relates to a device for measuring the axle load of a motor vehicle.

[0002] It is an object of the present invention to determine the axle load of motor vehicles in as simple and inexpensive a manner as possible, and in particular to avoid overloading of the motor vehicle, which may lead to dangerous driving states and therefore to a danger of traffic accidents.

[0003] The object according to the invention is achieved by the fact that at least one extension-sensitive resistor is arranged on at least one component of a motor vehicle which is subject to a change in shape as a function of the load, with at least one insulating layer being arranged in between.

[0004] The device according to the invention is preferably designed in such a manner that the component serves as a metallic support for the at least one extension-sensitive resistor, and that at least one further conductor track, which is connected to at least one conductor track of the extension-sensitive resistor, is applied to the surface of the metallic support.

[0005] The measures which are listed in the further subclaims allow advantageous refinements and improvements to be made to the invention described in the main claim.

[0006] Devices according to the invention can be arranged at various points on the chassis which are subject to load and are able to detect individual stresses, so that it is possible to determine how the load is distributed. A central electronic control unit is then able to process these force-action signals and to use comparison software to determine whether there is any danger to the occupant(s) of the vehicle and ultimately to traffic as a whole as a result of the permissible gross weight having been exceeded.

[0007] By way of example, if an overload is detected, this could lead to the motor vehicle becoming impossible to start or to the driver being warned of this fact.

[0008] The invention allows numerous embodiments. One of these is diagrammatically depicted in the drawing with reference to a number of figures and is described below. In the drawing:

[0009]FIG. 1 diagrammatically depicts the arrangement of devices according to the invention on a motor vehicle,

[0010]FIG. 2 shows a first exemplary embodiment, and

[0011]FIG. 3 shows a second exemplary embodiment of a sensor used in a device according to the invention.

[0012] Identical parts are provided with identical reference numerals throughout the various figures. FIGS. 2 and 3 each show enlarged excerpts of sectional illustrations, in which in particular the layer thicknesses are greatly exaggerated.

[0013]FIG. 1 diagrammatically depicts parts of a motor vehicle which are required for explanation of the invention, with a body 11, an axle 12, wheels 13, 14 and springs 15, 16, which are supposed to represent the entire suspension system, including suspension links, springs and shock absorbers. On the axle 12 there are in each case two sensors 17, 18, which measure the extension of the axle beneath the springs 15, 16 and therefore the bending moment of the axle 12. Therefore, the load which acts on the axle 12 from the wheels 13, 14 is also measured indirectly. The signals which are output by the sensors 17, 18 are fed to a measurement circuit 19, which calculates the load from the signals and controls a display device 20.

[0014] Advantageous sensors are explained below in connection with FIGS. 2 and 3. An extension-sensitive resistor 1 is connected to two conductor tracks 2, 3. These are applied to an insulating layer 4, which in turn is mounted on a further insulating layer 5. A steel support 6, which in the case illustrated in FIG. 1 is the axle 2, has on its surface an oxide layer 8 which results from manufacturing conditions and is merely indicated in the figures.

[0015] In the exemplary embodiment shown in FIG. 1, a conductor track is applied to the support 6 as a result of first of all a conductor track paste being printed on, and then this paste being fired at elevated temperature. During the firing operation, silver atoms penetrate into the oxide layer, so that the latter is “cracked”. As a result, a connection of good conductivity is created between the support 6 and the conductor track 7. The insulating layers 4 and 5 have holes into which conductor track paste penetrates during application of the conductor track 3, thus producing a conductive connection between the conductor track 7 and the conductor track 3.

[0016] In the exemplary embodiment shown in FIG. 2, to make contact with the support 6 there is only a conductor track 7′, which runs at the edge of the insulating layer 5 and is connected to the conductor track 3 via a connecting conductor track 10. The conductor tracks 3, 7′ and 10 can be produced in a simple manner, as can the conductor track 2, in a single operation. 

1. A device for measuring the axle load of a motor vehicle, characterized in that at least one extension-sensitive resistor (1) is arranged on at least one component (12) of a motor vehicle which is subject to a change in shape as a function of the load, with at least one insulating layer (4, 5) being arranged in between.
 2. The device as claimed in claim 1, characterized in that the component serves as a metallic support (6) for the at least one extension-sensitive resistor, and in that at least one further conductor track (7, 7′), which is connected to at least one conductor track (3) of the extension-sensitive resistor, is applied to the surface of the metallic support (6).
 3. The device as claimed in claim 2, characterized in that the at least one further conductor track (7) is arranged between the at least one insulating layer (4, 5) and the metallic support (6), and in that at least one conductive leadthrough is provided from the further conductor track (7) to the at least one conductor track (3).
 4. The device as claimed in claim 2, characterized in that the at least one further conductor track (7′) is applied to the metallic support (6) next to the at least one insulating layer (4, 5), and in that the at least one further conductor track (7′) is connected to the at least one conductor track (3) with the aid of a connecting conductor track which leads over the surface of the at least one insulating layer (4, 5).
 5. The device as claimed in one of the preceding claims, characterized in that the at least one further conductor track (7, 7′) consists of silver.
 6. The device as claimed in one of the preceding claims, characterized in that signals from extension-sensitive resistors (1) which are arranged at various locations (17, 18) of the motor vehicle can be fed to a processor (19) for analysis and display (20). 